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Diffusion-weighted magnetic resonance imaging characteristics of hemorrhagic transformation in experimental embolic
M A Yenari1, C Beaulieu, G K Steinberg
1Department of Neurology, Stanford Stroke Center, Stanford University Medical Center, CA, USA.
Abstract:
Diffusion-weighted magnetic resonance imaging (MRI) can detect ischemia within minutes of onset, but its ability to reliably detect hyperacute cerebral hemorrhage is unknown. The present study characterized diffusion-weighted, T2-weighted, and contrast-enhanced T1-weighted MRI appearances of hemorrhagic transformation within 5 hours of onset in experimental embolic stroke. Apparent diffusion coefficients and MRI signal characteristics were noted within corresponding regions of hemorrhage observed on gross pathology. Apparent diffusion coefficients were significantly increased within hemorrhagic lesions, but were still within the expected range for bland ischemia. The appearance of the hemorrhagic lesions on diffusion-weighted MRI was also very heterogeneous and not very useful for clinical screening. Other MRI modalities should be investigated, but computed tomography remains the only widely available clinical method of reliably detecting cerebral hemorrhage.
Insights
Diffusion-weighted MRI shows increased diffusion in hemorrhagic stroke, but it is not reliable for early detection. Computed tomography remains the standard for diagnosing hyperacute cerebral hemorrhage.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Diffusion-weighted magnetic resonance imaging (MRI) is sensitive to acute ischemic stroke.
- The utility of diffusion-weighted MRI for detecting hyperacute cerebral hemorrhage is not well-established.
Purpose of the Study:
- To characterize the MRI appearance of hemorrhagic transformation in experimental embolic stroke within 5 hours of onset.
- To evaluate the reliability of diffusion-weighted MRI for detecting early cerebral hemorrhage.
Main Methods:
- Experimental embolic stroke model in animals.
- Diffusion-weighted, T2-weighted, and contrast-enhanced T1-weighted MRI were performed.
- Apparent diffusion coefficients and signal characteristics were measured in hemorrhagic lesions and correlated with gross pathology.
Main Results:
- Hemorrhagic lesions showed significantly increased apparent diffusion coefficients, overlapping with values typical for ischemic stroke.
- Diffusion-weighted MRI appearance of hemorrhagic lesions was heterogeneous and not consistently indicative of hemorrhage.
- T2-weighted and contrast-enhanced T1-weighted MRI findings were not detailed in the abstract.
Conclusions:
- Diffusion-weighted MRI is not a reliable method for detecting hyperacute cerebral hemorrhage.
- The heterogeneous signal characteristics and overlapping diffusion values limit its clinical screening utility for hemorrhage.
- Computed tomography remains the primary clinical tool for diagnosing cerebral hemorrhage.